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46                          Wood-tiirning L athes.

The flexible plane is very useful for truing large concave or
convex surfaces, a symmetrical curvature being given to the sole by
.simultaneous adjustment at front and back.

Of machine tools, two or three lathes are required ; the first,
with a long bed and two headstocks, Fig. 59 ; the second, a large
face lathe for turning wheel rims, Fig. 60; and the third, a light
face lathe for small articles, Fig. 61. Their speeds must be con-
siderably above those used for iron turning. A tool rest is used
to them all, and the work is done entirely by hand, the tools
necessary having such edges as are sketched at Fig. 62.

The mandrel of the lathe is provided with a chuck, which has
a different form for each lathe; jthus, the face lathe has a screw on
the mandrel to receive the flange chuck (see A, Fig. 60), and the
face plate on which the pattern is turned is supplied by a disc of
wood bolted to the chuck. The lathe with the two headstocks is
provided with a chuck of the form shewn at B, Fig. 59, which is
well pressed into the end of the pattern, and so compels the
latter to turn with the mandrel; and in the small lathe, the
pattern is screwed on the mandrel at c.

Other machine tools required are :a band saw, circular saw,
and, if possible, a wood-planing, machine.                                  i

Arrangement of Mould--It is the duty of the pattern
maker to so arrange the moulding of his pattern as to cheapen
it (the moulding) to the utmost, and give the least trouble in
the foundry.    Thus, if the mould is to be in green sand, as
little dried core work is to be \ used as possible, and very ofteta
a great deal may be done by? the introduction of loose pieces,
i which are left in the sand after the body of the pattern has been
; withdrawn, and are then removed in another direction (see A,
, Fig. 30).    He should put as litjtle of the pattern in the top box
as is practicable, for it is evident that this part of the mould
must receive the worst treatment, being lifted off and turned over,
perhaps more than once.   Added to this, the fact that the cope
has to be taken away so as to leave the pattern behind, means the
; using of a good deal of care, despite which much broken sand
\ may still appear; while the half pattern in the bottom box may be
; *| '                    ' lifted in full daylight, and no accident need happen to it.   We

*'**                       may here mention generally the method of withdrawing trouble-